After cicada, firefly's warm glow grows

Stephen KiehlSun Staff

We cherish the firefly a little more this year. The luminescent insects have always had good timing. They arrive in mid-June to tell us that school is over and summer is here. They bring warm nights and long days. They give license to run through the grass barefoot and jump at the sky.

But this year their timing is even better. This year they arrive on the heels of the cicadas (remember them?), those boorish, clumsy bugs that flew into our hair and down our shirts and made such an awful racket. We are blessed with the fireflies every year, but it's only every 17 years that we are reminded how extraordinary they really are.

They are a modest insect. They go about their business quietly, efficiently even, and we do not get hysterical about it. Their arrival is not heralded by breathless reports on the TV news or "Firefly Watch" columns in the newspapers. When they fly into our living rooms, we do not roll up a magazine or reach for the Raid. No. We gently cup them in our hands and release them outdoors.

The firefly is like a highly evolved version of the cicada - smaller, sleeker, graceful, refined. It is Cicada Version 2.0. Or maybe Version 10.0.

But both bugs are here to do the same thing: make more of themselves. And their life cycles are remarkably similar, give or take a few years. They both spend time in the larval stage, living mostly underground. Eventually - after two years for the firefly and 17 for the Brood X cicada - they emerge from the earth and take flight. They have just a few weeks to mate and reproduce, and then they die.

The difference, of course, is in how they do it. The cicada is like the loud drunk at the bar who thinks the more noise he makes, the more women he will attract. (If only that guy appeared once every 17 years, too.) The cicadas hang from our tree branches and leaves and drone all day at levels approaching 90 decibels - equivalent to a lawnmower - in their quest for a mate.

The male firefly is more subtle. He emerges about an hour before sunset and announces himself through those soft yellow-green flashes. Recent research has found that males who sustain their flash longer are more attractive to females because it means they have more nutrients to pass on to the offspring. But the difference - fractions of a second - is hardly noticeable to us.

Easy catches

Because fireflies tend to fly low to the ground and are not very fast, they are easy prey for children. In Baltimore in the 1950s, thousands of children caught fireflies and took them to Johns Hopkins University researchers, who paid 25 cents per hundred live bugs. In the summer of 1952, one boy turned in more than 37,000. Some feared the area's firefly population would be wiped out, but if it was ever threatened, it has recovered nicely.

"For whatever reason, the greater Washington area is a major epicenter of firefly activity. There are many, many species," says Jonathan Copeland, a biology professor at Georgia Southern University and one of the country's top firefly authorities. "It probably has something to do with how humid, how hot, how moist it is."

So catch all the fireflies you want. The only downside may be the foul smell they leave on your hands. The odor comes from defensive chemicals the fireflies secrete to deter predators. Birds, spiders and lizards have learned that fireflies will make them sick, so they leave them alone. Their coloration is also a warning.

"They're black and yellow and red, which across the animal kingdom is a warning to predators: 'Don't eat me. I taste bad,' " says Sara Lewis, a firefly expert and biology professor at Tufts University near Boston.

With few predators, save pesticides and concrete, fireflies have done well. One night last week in a field in Woodlawn, they were floating by the hundreds a few feet above the tall grass, nature's paparazzi flashing every five seconds and then scanning the ground to search for a reply signal from one of the females, which perch on leaves or blades of grass.

People run to fireflies, not away from them. They do not squawk when you catch them. Instead, they gingerly walk along the edge of your hand, producing a barely perceptible tickling sensation. They tend to stop flashing when we catch them, though. They want nothing to do with us.

The Ohio State University Extension Office says this about fireflies on its Web site: "They don't bite, they have no pincers, they don't attack, they don't carry disease, they are not poisonous, they don't even fly very fast."

Fireflies around the world

And so it is sad to learn that there are some places of the country not graced by the flickering of fireflies on summer evenings. In much of Canada and west of the Rockies, there are no fireflies. It may be too cold for them in Canada, but scientists aren't sure why they're missing from the Western United States.

"They just never made it out there," Lewis says. "That's one of the big disadvantages of living in California or Oregon or Washington."

Fireflies can be found in much of the world, but the ones in Southeast Asia are most interesting. Whole packs of them have synchronized their flashing, and scientists aren't sure why. (One synchronous species has also been documented on Maryland's Eastern Shore.) Such fireflies have drawn the attention of not just biologists but mathematicians like Steven Strogatz of Cornell University.

"They're most conspicuous along the tidal rivers that lead out to the sea," Strogatz says, "and they perch themselves on the leaves of mangrove trees, and males of several different species have this unbelievable ability to flash in unison by the thousands all night long."

It's probably not surprising that Robert Frost wrote a poem about lightning bugs. He called it "Fireflies in the Garden," and he wrote that they "Achieve at times a very star-like start/Only, of course, they can't sustain the part."